The need to attach electrical components such as wires and the like to insulation bodies is usually satisfied by bolting the component into the body. The insulator bodies are usually made of porcelain and any threads in such porcelain bodies are so difficult to produce that they are rarely, if ever, made. If they were produced for some specific reason, a bolt or other fastener inserted into these threads easily strips the threads so that the attached component easily pulls loose from the insulator body. To make attachments to porcelain, it is conventional to cement a metal cap to the insulator body and to attach the electrical components to the metal cap.
The conventional metal caps have three major disadvantages, namely they present a large area of conductive metal, the cap is the most expensive part of the insulator structure, and the incompatability of the thermal characteristics between the metal and the porcelain gives rise to additional problems. Despite these disadvantages, the metal cap has been considered necessary and is in widespread commercial use.
It has now been discovered that if an insulator body is made of a particular material and threads are formed in that body in a particular way, the metal cap and its associated disadvantages can be completely eliminated. The threads formed are even stronger than the rest of the insulator body.